Settlement predictions in the Anatolian Motorway, Turkey

Abstract

The Anatolian Motorway through the Asarsuyu Valley passes across the landslides which have been extensively disturbed by past fault movements. The Asarsuyu Valley is the most important crossing of the motorway between Istanbul and Ankara route. Along the Asarsuyu Valley, about 7 km of the roadway is still under construction. In this study, the magnitude and the rate of the settlement over consolidated clays in lacustrine deposits within the Asarsuyu Valley were compared with each other. On the basis of field observations and laboratory test results, it was determined that the lacustrine deposits were eroded up to 15 in by the river in the valley bottom. As results of unloading and desiccation process, the clay layers are overconsolidated. Settlement calculations indicate that the amount of clay layers has caused the intolerable consolidation settlement under the concrete structures and motorway embankment. In this respect, preloading embankment on clay and silty clay deposits was projected and constructed. On the basis of evaluations, estimated values of settlement are lower than those realized. However, the predicted settlement quantities are found reliable and comparable to field measurements. On the other hand, significant differences were observed between calculated and measured rate of the settlement. The high rate of the settlement, which was measured during preloading, was caused by the viscoelastic strain due to the relatively high load and sandy pockets available in the clay layers, but was not detected by the drilling and the micro/macro texture of the clay layers, (C) 2002 Elsevier Science B.V. All rights reserved.